Yellow goo on sump silicone

[bzb]

I thought maybe I didn't let the silicone cure long enough, but this goo is also on the factory silicone. The water does slip by the cups/socks and drip toward the baffle far more than it drips along the glass edge.

I can wipe it off for the most part (can't get the stuff below the sock chambers) but even after a thorough wiping during a water change, it looks like it stained the silicone. It's in very random spots on the next chambers - water level is a little high right now after adding a new rock last night, but it seems to start yellowing right where the water line typically is.

Assuming it's just organic muck, but wanted to throw this out to yall to see if it's anything I should be concerned about.

Amm: 0
Nitrite: 0
Nitrate: <5ppm
pH: 8.1
Temp: 78-80

 

[dball711]

What brand of silicone did you use

 

[bzb]

GE Silicone 1 (white/blue tube), purchased at Home Depot.

But it's on the factory silicone, too.

 

[ActiveAngel]

Perhaps it could be an iron (or iodine) contamination; both of those are capable of producing compounds of this color. Do you have any steel or other metallic things in the water?

Usually, things such as a single steel hose-clamp isn’t enough to do this. But the idea of contamination is worth consideration.

Given that it’s stronger near the water surface, maybe an iron oxide. Just brainstorming; I don’t know for sure

 

[bzb]

Nothing metallic that I'm aware of outside of the pumps. Maybe something that was in my dry rock? It was cooking in a bin for about a month.

It's weird, right? It's generally not where it's submerged, but above wherever my water line might have been at one time.